9: Inflammatory Breast Cancer: durable Breast Cancer-specific Survival for HER2+ Patients with a Pathologic Complete Response to Neoadjuvant Therapy

Saturday, March 12, 2022

9:34 AM – 9:42 AM CST

Location: Chantilly East

Abstract Presenter(s)

Tina J. Hieken, MD

Professor of Surgery
Mayo Clinic
Rochester, Minnesota, United States

Disclosure: Genentech (Individual(s) Involved: Self): Research Support, Research Support; SkylineDx (Individual(s) Involved: Self): Research Support

Participants should be aware of the following financial/non-financial relationships:

Tina J. Hieken, MD: Genentech (Individual(s) Involved: Self): Research Support, Research Support; SkylineDx (Individual(s) Involved: Self): Research Support

Introduction:

Inflammatory breast cancer (IBC) has a poor prognosis despite trimodality treatment with neoadjuvant chemotherapy (NAC), modified radical mastectomy and adjuvant radiation. With recent systemic therapy advances, particularly dual agent targeted regimens, we investigated whether improved pathologic complete response (pCR) rates and early recurrence-free survival (RFS) translate into durable long-term response.

Methods:

With IRB approval, we studied cT4dM0 IBC patients operated on at our institution 10/2008-7/2015. Comparisons were performed by chi-square tests. Kaplan-Meier and log-rank tests were used to analyze survival.

Results:

All 57 patients received NAC and operation; 54 (95%) had postmastectomy radiation. No patients received response-directed adjuvant chemotherapy. Tumor subtype was HER2+ in 25 (44%), ER+/HER2- in 17 (30%), and ER-/HER2- in 15 (26%). 52 (91%) were clinically node-positive. Total (in both the breast and axilla) pCR rates differed by approximated biologic subtype (p< 0.001). With 84 months median follow-up, 23 patients recurred – 19 (82%) with distant disease as first recurrence. Five-year RFS was 83% for HER2+ disease, 53% for ER+/HER2- disease, and 40% for ER-/HER2- disease, p=0.009, while 5-year BCSS was 100%, 77%, and 43%, respectively, p=0.005. Ten-year RFS and BCSS were 74% and 86% for HER2+ patients among whom 14/25 (56%) had a pCR. After 108 months median follow-up, HER+ patients with a pCR had no recurrences, associated with 5- and 10-year RFS and BCSS rates of 100%. For HER2+ patients without a pCR, 5/11 relapsed at a median of 38 months after diagnosis for a 5-year RFS of 64% (p=0.002 versus HER2+ patients with a pCR) (Figure) and 3/11 died of breast cancer, all within 72 months of diagnosis.

Conclusions:

Patients with HER2+ IBC have a high rate of pCR to neoadjuvant systemic therapy. Those patients treated with trimodality therapy and a favorable pathologic response have a durable survival benefit. In the future, further improvement in outcomes for IBC patients without a pCR may be seen when response-driven adjuvant chemotherapies such as T-DM1 are administered.

Learning Objectives:

Upon completion of this activity participants will understand differences across approximated biology subtype to neoadjuvant systemic therapy in inflammatory breast cancer patients.
Upon completion of this activity participants will appreciate high response rates to neoadjuvant systemic therapy in HER2+ inflammatory breast cancer patients.
Upon completion of this activity participants will recognize that a pathologic complete response to targeted and chemotherapy confers a durable recurrence-free and breast cancer specific survival benefit.